| Posted: Mar 24, 2015 |
Possibilities for graphene-integrated polymer composites in dental prostheses ans medical implants
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(Nanowerk News) A larger proportion of our population is now living into their 80s and 90s and this has a great deal of influence on the frequency with which either partial and complete tooth loss occurs. There are other causes of edentulism outside of an ageing demographic of course - congenital absence, trauma, dental diseases and oral cancers all significantly contribute to it too. All of these factors, as well as increased interest in oral health within developing countries, are leading to a considerable growth in the value of the global dental prosthetic supply business. It is expected that this will be worth approximately $9.1 biliion by 2018, according to industry analysts Markets&Markets (an almost 50% increase on its current value). Around half of this will be related to fixed dental prostheses (either implant-supported bridges/crowns, tooth-supported bridges/crowns, inlays, onlays or veneers). If this the predicted increase in the market is to be witnessed, however, then major advances must be made in prothestic science.
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Numerous approaches have been taken to the construction of fixed dental prostheses, but existing material technologies have tended to fall short of expectations. The reason for this is an inherent lack of robustness, which leads to short operational lifespans being witnessed. Conversely, the period of time that prostheses need to function is being extended as the average life expectancy increases. There is an increasing demand within the dental industry for prosthetic materials which display increased overall resilience and permit greater longevity.
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One of the main problems associated with the fitting of patients with fixed dental prostheses is that of location. This stems from the fact they must be situated within the mouth - which proves to be an extremely demanding setting, where exposure to moisture, high temperatures, abrasion from toothbrushes and intake of food all have to be dealt with. These conditions can lead to complications, mechanical failures and contraindications occuring, all of which negate clinical success and over time mandate remedial work to restore the prosthetic to full working order - with associated cost and inconvenience. Then there is the issue of biocompatibility to consider. It is critical that any prostheses can coexist harmoniously with the organic tissues they are in contact with.
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The regularity with which failures currently occur prevents the specification of prostheses with operational lifespans which are in line with the patients (i.e. capable of functioning over decades rather than just years). This is something that must be satisfied before fixed dental prostheses are to gain widespread acceptance.
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To try and meet these requirements, a number of materials have been investigated in recent times - including metals (such as aluminium and tin), ceramics (zirconium and porcelain) and metal-ceramic hybrids. These materials have sadly proved inadequate in terms of their mechanical properties and their biocompatibly. Initiation of allergen sensitivity, potential for cytotoxicity, inability to blend in well enough with surrounding teeth/gums are other factors that need to be taken into account.
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Poly-ether-ether-ketone (PEEK) is an organic thermoplastic polymer material which is already employed in some medical implants due to its compatibility with human tissues. By integrating graphene into this polymer is hoped that the high degree of ruggedness that is mandated by dental use can be achieved. Graphene solutions provider 2-DTech and dental implant specialist Evodental are currently in the process of carrying out preliminary investigative work into the prospects of applying graphene within the field of dentistry. Utilising composites featuring high grade graphene they are looking to produce PEEK-based fixed dental prostheses with markedly increased longevity and improved clinical function. The objective of the project is to incorporate microscopic disc-shaped particles of graphene (known as graphene nanoplatelets) into the PEEK in order to form a graphene-reinforced polymer that is strong enough for dental prostheses (leading to a marked reduction in the number of clinical/surgical procedures needed to carry out repairs) while better matching the surface properties of the bone accommodating it and teeth around it.
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Combining an ultra-thin structure with high durability, the graphene-reinforced polymer envisaged by 2-DTech and Evodental could mitigate the deficiencies of current fixed dental prostheses construction methodologies. The resulting prostheses will benefit from the strength of graphene. Furthermore, since graphene coatings are completely transparent they have no effect on the prostheses’ visual appearance.
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Graphene-based polymer composites, such as the one described in this article, have the potential to revolutionise dentistry, enabling production of dental prostheses that are better able to cope with hostile operational environments. This will allow for greater prevalence of oral rehabilitation and thereby decrease the level of edentulism in the global population.
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